The phase behavior of the dioctyldimethylammonium bromide (DODAB)–sodium bis(2-ethylhexyl)sulfosuccinate (AOT)–water system was determined. Studies dealt with dilute concentration regimes, at an overall surfactant concentration lower than 30.0 mmol kg−1, and in the cationic rich side. The system was investigated by combining visual inspection with optical microscopy, fluorescence microscopy, dynamic light scattering, small-angle X-ray scattering, and electrophoretic mobility. At high [DODAB]/[AOT] mole ratios, stable and unilamellar catanionic vesicles are observed in a narrow region of the phase diagram. Vesicles are characterized by nearly constant hydrodynamic diameters, in the 300–400 nm size range, and positive ζ-potentials (about 40–50 mV). A further increase of AOT content induces the onset of a biphasic region, where vesicles are in equilibrium with a lamellar phase. In the above concentration regimes, addition of sodium bromide destabilizes vesicles and favors the formation of a lamellar phase. Under the same conditions, conversely, a synthetic polyelectrolyte, sodium polyacrylate, does not alter the phase behavior. It induces the growth of particle size and decreases the ζ-potential. The complexes formed by catanionic vesicles and sodium polyacrylate aggregate and form clusters, and readily re-dissolve when more polymer is added.
The DODAB AOT water system: vesicle formation and interactions with salts or synthetic polyelectrolytes / C., Pucci; A., Salvia; Ortore, Maria Grazia; C., La Mesa. - In: SOFT MATTER. - ISSN 1744-683X. - STAMPA. - 9:(2013), pp. 9000-9007. [10.1039/c3sm51624e]
The DODAB AOT water system: vesicle formation and interactions with salts or synthetic polyelectrolytes
ORTORE, Maria Grazia;
2013-01-01
Abstract
The phase behavior of the dioctyldimethylammonium bromide (DODAB)–sodium bis(2-ethylhexyl)sulfosuccinate (AOT)–water system was determined. Studies dealt with dilute concentration regimes, at an overall surfactant concentration lower than 30.0 mmol kg−1, and in the cationic rich side. The system was investigated by combining visual inspection with optical microscopy, fluorescence microscopy, dynamic light scattering, small-angle X-ray scattering, and electrophoretic mobility. At high [DODAB]/[AOT] mole ratios, stable and unilamellar catanionic vesicles are observed in a narrow region of the phase diagram. Vesicles are characterized by nearly constant hydrodynamic diameters, in the 300–400 nm size range, and positive ζ-potentials (about 40–50 mV). A further increase of AOT content induces the onset of a biphasic region, where vesicles are in equilibrium with a lamellar phase. In the above concentration regimes, addition of sodium bromide destabilizes vesicles and favors the formation of a lamellar phase. Under the same conditions, conversely, a synthetic polyelectrolyte, sodium polyacrylate, does not alter the phase behavior. It induces the growth of particle size and decreases the ζ-potential. The complexes formed by catanionic vesicles and sodium polyacrylate aggregate and form clusters, and readily re-dissolve when more polymer is added.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.